A DPIM-InSAR method for monitoring mining subsidence based on deformation information of the working face after mining has ended. Issue 16 (18th August 2021) - Chuang, Jiang
ABSTRACT: The mining of underground coal resources causes long-period and large-gradient deformation of the overlying surface of the working face. Due to the characteristic of long period of deformation, D-InSAR (Differential Interferometry Synthetic Aperture Radar) technology can be easily affected by temporal incoherence. When the surface deformation gradient exceeds the monitoring gradient of D-InSAR technology, the conventional D-InSAR technology will easily cause unwrapping failure, and thus is difficult to realize 3D (Three Dimensional) monitoring of mining-induced surface deformation. In order to solve the problems, a prediction method of 3D surface deformation based on D-InSAR and constraints of DPIM (Dynamic Probability Integral Method) model was studied in this paper. Firstly, SAR image data of the working face after the end of mining were processed by differential interference to obtain the LOS surface deformation during a period of time after the mining. Secondly, according to the relationship between D-InSAR LOS (Line Of Sight) deformation and 3D surface deformation, the D-InSAR observation equation for mining subsidence based on DPIM constraints was constructed. Then, the solution method of the condition equation of DPIM-InSAR (Interferometry Synthetic Aperture Radar) based on GA (Genetic Algorithm) was constructed. Finally, based on obtained LOS deformation, the 3D surface deformation of surface subsidence was obtained using the 3D prediction method based on DPIM-InSAR. The results of simulation experiments effectively verified the feasibility of the method. Differential interference processing was performed for Sentinel-1A data after the mining. The LOS deformation of the 1613 working face of Guqiao South Mine between 20 January 2018 and 25 February 2018 was obtained. 3D surface deformation from the beginning of the mining to completion was obtained using the proposed prediction method of 3D surface deformation and subsidence based on DPIM-InSAR (Dynamic Probability Integral Method). The predicted subsidence values were compared with the measured values. The results showed that the fitting errors of the LOS deformation were mostly within 3 mm. The fitting mean square error was ± 2.37 mm (accounting for 6.7% of the maximum LOS deformation value), and the fitting accuracy was high. The fitting mean square error of subsidence was ± 120 mm (accounting for 7.3% of the maximum subsidence). The results in engineering application show that the proposed 3D predicting method of surface deformation and subsidence based on DPIM-InSAR has certain practical values.